panic: lock (sleep mutex) vnode interlock not locked

Hello,

on a recent -Current on an SMP mobo, I get the following panic :

FreeBSD 7.0-CURRENT #750: Sun Aug  7 02:57:37 CEST 2005
    XX_at_YYY:/usr/obj/usr/src/sys/GENERIC
WARNING: WITNESS option enabled, expect reduced performance.
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Pentium II/Pentium II Xeon/Celeron (334.09-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0x665  Stepping = 5
  
Features=0x183fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,MMX,FXSR>
...
panic: lock (sleep mutex) vnode interlock not locked 
_at_ /usr/src/sys/kern/vfs_subr.c:750
cpuid = 0
KDB: enter: panic
[thread pid 49 tid 100039 ]
Stopped at      kdb_enter+0x2b: nop
db> where
Tracing pid 49 tid 100039 td 0xc12a3960
kdb_enter(c085a50f) at kdb_enter+0x2b
panic(c085e290,c0875751,c085dc1d,c0863291,2ee) at panic+0x127
witness_unlock(c19693ac,8,c0863291,2ee) at witness_unlock+0xbc
_mtx_unlock_flags(c19693ac,0,c0863291,2ee) at _mtx_unlock_flags+0x5b
vdestroy(c1969330,c1969330,c7228cec,c0684ed5,c1969330) at vdestroy+0x1b5
vdropl(c1969330,7,c12a3960,c0907700,c1969330) at vdropl+0x3e
vlrureclaim(c13c3800,c12a3960,c12a2830,c06850b0,c12a2830) at vlrureclaim+0x1fd
vnlru_proc(0,c7228d38,0,c06850b0,0) at vnlru_proc+0x18b
fork_exit(c06850b0,0,c7228d38) at fork_exit+0xa0
fork_trampoline() at fork_trampoline+0x8

the machine was running cvs over an ssh link :
# cd /usr/src
# cvs -qR up -Pd
U ObsoleteFiles.inc
...
U rescue/librescue/Makefile

(no kernel dump)

	TfH